You can get some great pictures in low light, but only if you know how, and when, to use your camera’s ISO settings. In this tutorial we show you everything you need to know.
Your camera can automatically set the exposure in any conditions, even indoors or at night. To do this it adjusts the lens aperture and uses slower shutter speeds so that the sensor is exposed for longer.
There comes a point, though, when the shutter speed is so slow that there’s a danger the camera will move during the exposure, leading to camera shake and horribly blurred pictures.
It’s difficult to give hard and fast rules about when camera shake might start to creep in, but as soon as you see shutter speeds of 1/30 sec or slower displayed in the viewfinder, you’re in danger territory.
If your lens has an image stabilisation function, this will certainly help, but only up to a point.
The real answer is your camera’s ISO setting.
This is like turning up the volume on the sensor – it makes it more sensitive to light. Your camera can now use faster shutter speeds in poor light, and you can carry on getting sharp pictures.
ISO settings are adjusted on a fixed scale (see overleaf), and each step on the scale doubles the sensitivity.
But there is a payoff. As you increase the ISO settings, the digital ‘noise’ in your pictures increases too. This noise is like the grain in high-speed film, but more pixelated and less attractive. When you increase the ISO you’re trying to choose the best compromise between picture quality and usable shutter speeds.
You don’t always have to use a high ISO settings in low light, though. If you put the camera on a tripod, long exposures don’t matter because the camera won’t move – you can shoot at night using a low ISO for best quality.
So follow our guide to find out when, how and why to change your ISO settings to get the best possible light in what may be the worst possible lighting conditions.
How – and when – to use your higher ISO settings
01 What ISO settings are you using?
Do your shots look as blurry as this when you shoot indoors? That’s because the ISO setting on the camera is too low, and it’s using longer exposures (slow shutter speeds, in other words) to cope with the low light. At ISO200, the camera had to use a shutter speed of 1/5 sec.
02 Increasing the ISO
On our Nikon D300s, we press the ISO button on the back of the camera and turn the command dial. On other models, you can use the Shooting menu or the interactive display. If you increase the ISO from 200 to 3200, the camera can use shutter speeds four stops faster.
03 Sharper shots
With the ISO set to 3200 we’re getting shutter speeds of 1/80 sec to 1/125 sec. That’s enough to dramatically cut the risk of camera shake, and it can also cope with a certain amount of subject movement, which is especially useful with fairground attractions and arcades.
04 Image stabilisation verdict
If your lens has IS, switch it on. This will help cut camera shake, but it has limitations. You may be able to shoot at shutter speeds up to four stops slower without shake, but it won’t help with moving subjects – here, there’s no substitute for higher shutter speeds.
05 Static subjects
VR can pay dividends with static subjects, though, and you can get away with shutter speeds as low as 1/15 sec, 1/8 sec or even slower. But take several shots, not one, to be sure of getting one that’s sharp. Continuous mode can be useful because it gives the camera time to settle.
06 Brace yourself!
In really dark environments, even a high ISO is no guarantee of fast shutter speeds. Here, we’re having to shoot at just 1/15 sec. In these situations, try to brace the camera or rest your elbow on a rigid surface.
ISO settings are the same across all cameras. The upper and lower limit varies from one DSLR to another, but the numbers are always the same. Many DSLRs also offer extra ‘Hi’ settings which extend the ISO range beyond the normal limits and don’t necessarily conform to the strict performance parameters of the regular ISO settings. ‘Hi’ modes produce more noise and softer detail, and while they’re useful in an emergency, generally they’re best avoided.
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